ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
471 
Mesochorus within Nematus , the development is usually incomplete, and 
the same is true of Platygaster larvae within the larvae of Cecidomyidae. 
Instinct of Ammophila affinis.* — Dr. P. Marchal has made many 
observations on the well-known habits of this sand- wasp which, like 
other Sphegidae, paralyses its victims by stinging the ventral ganglia. 
He concludes (1) that the habit is not wholly disinterested ; (2) that 
there are many gradations between the insect which kills and that which 
paralyses its victims ; (3) that the procedure is by no means stereotyped, 
but variable in details ; (4) that the stinging of the ganglia is not necessary 
to secure paralysis, indeed the sting must, from the nature of the victim, 
be often effected between the ganglia. None the less, Dr. Marchal 
admits the wonder of the instinct, and suggests, as Mr. Darwin also did, 
how the inefficacy of stinging the sides of the victim might lead to the 
habit of stinging the median ventral line, and eventually the ganglia. 
Moreover, the median ventral line is often the most convenient and 
natural line of attack. 
Classification of Sphegidaet — General 0. Radoszkowski has made 
a close study of the genital armature of these Hymenoptera, some of 
which have, while others have not, genital palps on the eighth segment 
of the abdomen. He urges that the classification based on the various 
characters of the genital apparatus is more natural than those founded 
on modifiable characters, and recognized as unsatisfactory by working 
entomologists. 
Hymenoptera fossoria.J — The sixth part of Herr A. Handlirsch’s 
monograph of these Wasps deals with the genus Stigus , of which 143 
species are fully diagnosed ; of these 44 are new to science. The com- 
pleteness of the author’s work may be imagined from the fact that 
hitherto never more than sixteen species have been described in one 
work. 
Roots of Alary Nerve of Coleoptera.§ — M. A. Binet, without any 
physiological experiments and merely by observation of microscopical 
preparations, has made an investigation into the roots of the alary nerve 
in various Coleoptera. There are two roots, one dorsal and one ventral. 
In apteric Coleoptera, as the author calls such forms as those in which 
the fore-wings are not used in flight, the dorsal root has disappeared 
from the nerve which goes to the elytra, while the ventral root is 
retained. M. Binet considers, therefore, that the ventral root is sensory, 
and the dorsal region of the ganglion motor. 
Male Generative Organs of Diptera.|| — Mr. N. Cholodkovsky has 
made a study of the male organs of a few Diptera, and especially of 
Laphria. He finds that the wall of the testicular tube consists of a thin 
but firm nucleated membrane, below which there is a structureless 
membrana propria. Epithelium is only found at the point of passage of 
the seminal duct ; this last, as well as the appended glands, has the 
same external membrane as the testis, while the vas ejaculatorium is 
surrounded by a thick, multilaminate membrane, which stains very 
* Arch. Zool. Exper. et Gen., x. (1892) pp. 23-86. 
f Bull. Soc. Imp. Nat. Moscou, 1891 (1892) pp. 571-96 (5 pis.). 
J SB. Ak. Wiss. Wien, ci. (1892) pp. 25-204 (3 pis.). 
§ Comptes Rendus, cxiv. (1892) pp. 1130-2. 
|| Zool. Anzeig., xv. (1892) pD 178-80. 
